Conventionally, a ball spline mechanism is known as a mechanism for causing a shaft disposed in a tip of a horizontal articulated type robot along the vertical direction to rotate around the center of the shaft and linearly move in the vertical direction (for example, refer to Japanese Unexamined Patent Application, Publication No. 2009-257458).
In this Japanese Unexamined Patent Application, Publication No. 2009-257458, a mounting member for mounting a work device such as a robot hand or the like is fixed to a lower end of the shaft.